The Cron Job/Crontab
To have your task run at this frequency, use the following cron:
0 */9 * * *
This cron command translates to the following (in Human-Readable format):
“Every 9 hours.”
What is a Cron Job & Crontab?
A cron job is a time-based task that is set to run at a specific interval. For example, a cron job could be set to run every day at midnight in order to update a database or send out nightly emails. Cron jobs are typically used for maintenance tasks that need to be performed regularly.
A crontab is a file containing commands and instructions for the cron daemon to execute. The crontab is used to schedule jobs (commands or shell scripts) to run periodically at certain times or dates.
Every cron job uses five fields. Here is an explanation of what each field does in this cron, which runs “every 9 hours“:
FUN FACT: Cron jobs are named after the Greek god of time, Chronos – so now you know where the name comes from!.
You might want to set up a crontab or cron job to run every 9 hours for several reasons, including:
- Checking if a server is still running every 9 hours
- Sending out a report every 9 hours
- Backup up data every 9 hours
Similar Cron Jobs
You might also want to run a crontab:
- every 8 hours
- every 3 hours
- every 1 hour
- every 12 hours
- every 4 hours
- every hour between 4:00 pm and 10:00 pm
- every hour between 4:00 am and 8:00 pm
- every 6 hours at 40 minutes past the hour
FUN FACT: When troubleshooting issues with cron jobs, it can be helpful to run them manually from the command line – this will allow you to see any error messages that might be generated..
In this article, you learned how to set up a cron job that runs every 9 hours. Please share this page with friends and colleagues if you find it useful.
If you have any questions, please don’t hesitate to comment below.
If you are looking for cron jobs that run at certain minutes, hours, days, weekdays, or months, or if you are looking for miscellaneous cron jobs, then check out our relevant sections, or visit our crontab cheat sheet for a list of hundreds of popular cron jobs.